1. Field of Invention
The present invention relates to an incinerator for solid wastes and in particular to a compact high temperature incinerator for bio-active solid waste with a counter-current heat recovery/transfer and a separate moisture removal.
2. Description of the Prior Art
Most prior art incinerators, for household wastes or bio-active solid wastes which has a large amount of bound and free moisture, have a large combustion chamber and a burner which supply additional heat to burn the wastes. The moisture is removed with other gaseous combustion products.
In these prior art devices, the temperature of combustion and rate of throughput are low. A large amount of unburnt wastes drops through a grating with ash and is disposed in landfill. The exhaust contains fly-ash and other air pollutants, such as Dioxin, NOx, and incomplete combustion products, which affect the surrounding area. Resulting strong public objections, known as not-in-my-back-yard or NIMBY, put most of the incinerators out of service except large ones with a well integrated air pollution abatement system. To make these large incinerators more economically attractive, the wastes are pre-sorted to increase their heating value and steam and power are generated as by-products.
More recently, cement kiln type, long-path incinerators are used to improve thermal efficiency of the added fuel. A rotating counter-current contact between the exhaust gas and the waste stream increases the temperature of the combustion, promotes the oxidation reaction and reduces the ash. To improve the thermal efficiency further, preheaters and heat recuperators are added. Although these are very popular in the catalytic or purely thermal oxidation of low concentration volatile organic chemicals (VOC), they are not widely used for household or medical wastes as they have a large amount of water and ash.
For a disposal of bio-active solid wastes, existing legal requirements make in-house incineration economically prohibitive. A contractor collects the wastes, sterilizes them in an autoclave, sorts and ships them to unpopulated areas for incineration and landfill. Sometimes, the wastes are lost overboard, wash up on beaches and cause hazard to bathers. This multiple handling of bio-active wastes wastes money, energy, and human effort and is dangerous.